The present invention relates to a heater and a method for generating an aerosol by application of heat to an indexing substrate.
Electrically powered systems for generating a flavorful aerosol from an underlying substrate are known.
For example, U.S. Pat. No. 5,060,671 incorporated herein by reference, describes an article in which a flavor-generating medium is electrically heated to evolve inhalable flavors or other components in vapor or aerosol form. A two-component device with a detachable heater/flavor generating medium portion is described. The heater/flavor generating portion, when used, may be discarded and replaced with a new heater/flavor generating portion. The power supply/control unit is reusable.
The article of U.S. Pat. No. 5,060,671 uses multiple heaters to heat discrete portions of the substrate. Sequential firing of the heaters is controlled by circuitry. Such circuitry and the multiple-heater arrangement are complex and can be costly to manufacture.
The concept of moving a circumferential heater down an extruded rod by automatic means mechanical or electromagnetic, is disclosed in U.S. Pat. No. 5,269,327 at column 7, lines 45-62.
U.S. Pat. No. 5,388,594 also describes an electrical smoking system for delivering flavors to a consumer. In that disclosure, a substantially cylindrical cigarette is inserted into a convenient hand-held lighter. The disclosure of that patent is incorporated herein by reference.
The cigarette is smoked normally and as a puff is taken, the pressure drop in the lighter causes one of a series of electrically resistive heaters to be fired. The electrically resistive heater heats the cigarette surface to a temperature which liberates certain tobacco flavors in a tobacco containing layer or the tobacco itself.
The pressure drop causes air to flow into the housing and into the cigarette. The vaporized products from the heated flavorful substrate flow through the cigarette body, through a filter, and then are ingested by the consumer.
Each heater is fired accordingly to an electronic control which selects the heater to be powered-up.
In each of these disclosures, a heat source is moved longitudinally down a cylindrical substrate either by mechanical or electronic manipulation.
Other methods of generating an aerosol from a substrate are known, e.g. from U.S. Pat. No. 5,479,948. That disclosure teaches moving a tobacco substrate in web form past an electrical heating structure in thermal proximity thereto. The web is provided in a container like an audio cassette tape, with the web replacing the magnetic recording medium on a dispense reel and a take-up reel.
Each of the above patents incorporated herein by reference, suffers from mechanical and electrical complexity, in requiring complex control circuitry, a plurality of heaters, or motors, gears, and reels. It is desirable to provide an electrical aerosol-generating article which generates an aerosol from a substrate, and which is simple, and inexpensive to manufacture.